I have been noticing that the lag spikes correlate with website lag. I have tested this a little but am not 100 % sure.
But I thought it might be worth mentioning to see if anyone else has noticed a similar trend.
Edit: I am now convinced after having the Hnh client and the Hnh website open at the same time in small window right beside each other. Every time there was lag, I would refresh the page. The website went white or didn't load the next page till the lag stopped in the game. Also check while it didn't lag and it loaded fine. I repeated this a couple times and got consistent results.
It makes sense that they correlate. They are run from the same server(right?).